Angus Reid Strategies' Jeff Vidler penned a terrific article (click to read it, pdf) "PPM Info: Too Much Of A Good Thing?" for the April 2009 print edition of Broadcast Dialogue magazine.
"Functionally, small sample sizes limit the accuracy of a lot of the minute-by-minute PPM data. This is particularly true when it comes to individual events."
It puts the issue of sample sizes in a slightly different frame, since PPM panelists have their meters moving for as long as 15 hours a day, seven days a week and the same people, more or less, comprise the sample for the entire survey periods for several years, rather than turning over every week as in diary measurement. Thus, we can drill down to one minute (or perhaps in the future, even shorter!) periods of listening.
"PPM gives you lots of tactical data but very little strategic information."
Yes, we know that the sample is tiny, but it's still fascinating to track. There's a lot of info there, following moment by moment what certainly looks like real radio usage by real folks, by and large.
"Most other products are consumed in the bright white light of day. You can see the clothes people wear and the cars they drive ... but radio is different. There's no price, no trackable transaction. And, being the one-to-one medium that it is, most people listen to radio by themselves."
Now that PPM has changed that. As Vidler writes, "if you've had the chance to see some of this (PPM) data, then you know it's more than a little intoxicating .. one taste isn't enough."
Is it that we only complain about samples when the results aren't to our liking? I don't think so, but these new-found abilities to drill down microscopically so much more than in the past will increase the pressure on ratings providers - radio's referees - to get and keep sample panels as representative and proportionally correct as possible.
Our futures (strategies and tactics) depend on it.